Endocrine Abstracts

Low-T₃ syndrome (euthyroid sick syndrome) develops in critically ill patients. Due to the catabolic state, accompanying critical illnesses, enhanced oxidative damage to macromolecules is expected to occur in subjects suffering from the low-T₃ syndrome.

The study aimed at evaluating the level of lipid peroxidation products in blood serum, collected from critically ill patients with the low-T₃ syndrome and at estimating the relationships between lipid peroxidation level and biochemical parameters and the survival rate.

The procedures, used in the study, were approved by the local Ethical Committee. Sixty (60) critically ill patients (among whom 20 patients met the criteria for the low-T₃ syndrome, and in 40 – thyroid hormones remained in normal ranges), as well as 20 healthy subjects (controls) were enrolled in the study. Peripheral blood was collected at different time points, depending on hospitalization periods in intensive care unit and the survival time. The concentration of malondialdehyde +4-hydroxyalkenals (MDA+4-HDA), as the index of lipid peroxidation, was evaluated in blood serum. The results were analyzed with respect to all the measured biochemical parameters, as well as to the further course of disease.

The level of lipid peroxidation was approximately twice as high in blood serum, collected from critically ill patients with the low-T₃ syndrome as in healthy subjects. Lipid peroxidation was also increased in the other group of critically ill patients, without low-T₃ syndrome, however, to a weaker extent than in the case of euthyroid sick syndrome. The level of lipid peroxidation corresponded with the mortality rate, which was – expectedly – higher in patients with the low-T₃ syndrome than in other critically ill patients.

Conclusions: Increased lipid peroxidation in critically ill patients, especially in those with the low-T₃ syndrome, may indicate enhanced oxidative damage to macromolecules, which may further contribute to organ disturbances.